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TI-2025-25204 Aliases CVE-2025-37856GHSA-ppp2-86mr-9vh3

btrfs: harden block_group::bg_list against list_del() races

Priority LOW 34Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 2 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.

Summary

In the Linux kernel, the following vulnerability has been resolved: btrfs: harden block_group::bg_list against list_del() races As far as I can tell, these calls of list_del_init() on bg_list cannot run concurrently with btrfs_mark_bg_unused() or btrfs_mark_bg_to_reclaim(), as they are in transaction error paths and situations where the block group is readonly. However, if there is any chance at all of racing with mark_bg_unused(), or a different future user of bg_list, better to be safe than sorry. Otherwise we risk the following interleaving (bg_list refcount in parens) T1 (some random op) T2 (btrfs_mark_bg_unused) !list_empty(&bg->bg_list); (1) list_del_init(&bg->bg_list); (1) list_move_tail (1) btrfs_put_block_group (0) btrfs_delete_unused_bgs bg = list_first_entry list_del_init(&bg->bg_list); btrfs_put_block_group(bg); (-1) Ultimately, this results in a broken ref count that hits zero one deref early and the real final deref underflows the refcount, resulting in a WARNING.

Why it matters now

EPSS 0.0031 23rd percentileScored 2026-11-07
Fix Partial Linux (Linux): 6.1.191, 5.16, 6.5 +5Red Hat: 2 without a fix

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux6.1.47 to before 6.1.191; 5.15.128 to before 5.16; 6.4.12 to before 6.56.1.191, 5.16, 6.5Patch availableCNA
LinuxLinux6.5 and later6.1.191, 6.6.160, 6.12.24, 6.13.12, 6.14.3, 6.15Patch availableCNA
  • Linux VendorLinux Affected 6.1.47 to before 6.1.191; 5.15.128 to before 5.16; 6.4.12 to before 6.5 Fixed in 6.1.191, 5.16, 6.5 Patch available CNA
  • Linux VendorLinux Affected 6.5 and later Fixed in 6.1.191, 6.6.160, 6.12.24, 6.13.12, 6.14.3, 6.15 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*before 6.12.24; 6.13 to before 6.13.12; 6.14 to before 6.14.3VulnerableLinux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions before 6.12.24; 6.13 to before 6.13.12; 6.14 to before 6.14.3 Vulnerable ·Linux

Remediation

  • Fix · CNA Linux (Linux) Fixed in 6.1.191, 5.16, 6.5
  • Fix · CNA Linux (Linux) Fixed in 6.1.191, 6.6.160, 6.12.24, 6.13.12, 6.14.3, 6.15

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 7AffectedNo fix planned: Out of support scope
Not affected: 3 products
  • Red Hat Enterprise Linux 10
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9

Timeline

  1. 2026-10-02 Threatist record created from CVE-2025-37856
  2. 2026-10-03 Alias added: GHSA-ppp2-86mr-9vh3
  3. 2026-10-21 Fix available: Linux/[email protected], Linux/Linux@9039afe6240ae01d6caf2fa731590ac74fb8a69b · CNA
  4. 2026-10-21 1 new reference · CNA
  5. 2026-10-30 Fix available: Linux/[email protected], Linux/Linux@ccb20413e7c82e4429c81f10d0e36cd9c0c643cd · CNA
  6. 2026-10-30 1 new reference · CNA

References

Patch 4

Other 2

  • TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
  • TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
  • TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
  • TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
  • TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
See all 15278 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences